PtdIns(3,5)P2 is an endogenous ligand of STING in innate immune signalling

  • Nature. 2026 Apr;652(8109):490-498. doi: 10.1038/s41586-025-10084-0.
Jay Xiaojun Tan  #  1  2  3  4 ,  Bo Lv  #  5  6 ,  Jie Li  7 ,  Tuo Li  8  9 ,  Fenghe Du  8  9 ,  Xiang Chen  8  9 ,  Xuewu Zhang  10 ,  Xiao-Chen Bai  7 ,  Zhijian J Chen  11  12  13
Affiliations
  • 1. Aging Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, PA, USA. [email protected].
  • 2. Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. [email protected].
  • 3. Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA. [email protected].
  • 4. Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX, USA. [email protected].
  • 5. Aging Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
  • 6. Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
  • 7. Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
  • 8. Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
  • 9. Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
  • 10. Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
  • 11. Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA. [email protected].
  • 12. Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX, USA. [email protected].
  • 13. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA. [email protected].
  • # Contributed equally.
PMID: 41639454 DOI: 10.1038/s41586-025-10084-0
Abstract

Exposure to cytosolic DNA triggers innate immune responses through cyclic GMP-AMP (cGAMP) synthase (cGAS)1,2,3. After binding to DNA, cGAS produces cGAMP as a second messenger that binds to stimulator of interferon genes (STING), a signalling adaptor protein anchored to the endoplasmic reticulum (ER)3-5. STING then traffics from the ER through the Golgi to perinuclear vesicle clusters, which leads to activation of the Kinases TBK1 and IKK and subsequent induction of interferons and other cytokines6-9. Here we show that phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2; also known as PI(3,5)P2) is an endogenous ligand of STING that functions together with cGAMP to induce STING activation. Proteomic analyses identified a constitutive interaction between STING and PIKfyve, an enzyme that produces PtdIns(3,5)P2 in mammalian cells. Deletion of PIKfyve blocked STING trafficking from the ER and TBK1 activation. In vitro reconstitution uncovered a strong and selective effect of PtdIns(3,5)P2 on STING activation by cGAMP. PtdIns(3,5)P2 bound directly to STING in fluorescence resonance energy transfer assays. Consistently, cryo-electron microscopy revealed that PtdIns(3,5)P2 promotes cGAMP-induced STING oligomerization10, functioning as a molecular glue. Similar to PIKfyve depletion, mutation of the PtdIns(3,5)P2-binding residues in STING largely blocked its trafficking and downstream signalling. These findings reveal that PtdIns(3,5)P2 is a lipid ligand of STING with essential roles in innate immunity.